Tang Yue unbuckled his seat belt, put the picture frame on the center console into his pocket, and then jumped down from the cab of the Martian stray dog, the old cat held his hand in the dark, in the current weather conditions, they must not get lost with each other, but the old cat and Tang Yue no longer have a safety rope this time, there is no rope to tie them together, the old cat can only hold Tang Yue tightly.

The old cat held a small emergency light in his paws and shook it in front of Tang Yue's eyes, "Follow me!" Tang Yue, can you hear me clearly? ”

Despite the proximity of a man and a cat, the quality of the radio calls was still terrible, and the large amount of charged dust suspended in the air severely interfered with the radio signals.

"I can hear you." Tang Yue nodded, "It's very clear!" ”

"We are still 3.5 kilometres from our destination, in that direction...... We need to go straight in that direction for 3,500 meters. The old cat stretched out its paws and pointed forward, "How are you doing?" How's the situation with the Mingguang armor? And how much oxygen and electricity are rich? ”

"I'm fine, I've had a full breakfast, and I'm full of energy." Tang Yue brushed away the sand and dust on the display of the Mingguang armor control terminal, and the terminal screen emitted a faint blue light, "The air pressure in the Mingguang armor is normal, the emergency oxygen system can work for at least ten hours, and the EVA battery can last for six hours." ”

"Okay." The old cat nodded, "I'll walk in front, and you follow me, with your hands on my shoulders." ”

Tang Yue put his hand on the old cat's shoulder, the old cat took a step and he followed a step, the old cat took the left foot, the old cat took the right foot, he took the right foot, like an old zombie in the Qing Dynasty.

Walking 3,500 meters in six hours was a piece of cake for Tang Yue in a normal environment, and he could complete the distance in six hours by jumping and walking on one foot.

But in a dust storm the situation is much more complicated.

For them, distance is secondary, and the biggest trouble is to identify the direction, if they accidentally get lost, the time spent in the dust storm will be greatly extended.

"Human walking cannot guarantee a strict straight line, so you have to correct the direction visually, and in the dark of night you will go around in circles in the dark of night when you can't see the reference." "A lot of times, you think you're walking in a straight line, but you're actually going in the right direction before you know it. ”

"Coriolis offset?" Tang Yue lowered his head, closed his eyes and moved forward step by step, this small broken step looked like an emperor penguin, since he couldn't see anything, Tang Yue simply closed his eyes, and the direction was completely guided by the old cat, like a blind man and his guide dog.

"The geoswiphic deflection force is one of the main reasons, and the main reason is that you can't guarantee that the stride length of the left and right legs is exactly the same." The old cat wears a cabin suit, walks the same carefully, there is no lighting, and the night vision device is not useful, the old cat can only grope forward, "Most people's right leg is slightly stronger than the left leg, so the stride of the right foot is larger than the left foot, this gap is very small, you yourself usually can't even see it, but in the desert for a long distance, this small gap will make you unconsciously deviate to the left, and finally go around a big circle back to the same place." ”

"So your left and right feet are equal?" Tang Yue asked.

"Yes." The old cat replied, "It's all strict and constant 0.4 meters." ”

"The legs are so short."

The old cat took Tang Yue forward, one foot deep and one foot shallow, there was a thick layer of floating sand on the ground, which could probably submerge Tang Yue's ankles, Tang Yue turned his head again, he couldn't see the Martian stray dog anymore, the old dog disappeared into the darkness, Tang Yue knew that he might never have the chance to meet it again in his life.

Tang Yue pinched the old cat's shoulder hard, he couldn't see the old cat's back, but he could see the lamp in the old cat's hand, the latter held the small emergency light above his head, which was the only light in the storm.

The old cat suddenly stopped.

Tang Yue also stopped, "What's wrong?" ”

"I need to make sure I'm not going in the right direction." The old cat stood still, "I'm blind like you now, and I'll go to the South Pole if I walk around with my head stuffed." ”

"But you have a map in your head."

"Maps have to have references to be used." The old cat slowly leaned down and grabbed a handful of sand, "Tang Yue, did you find it?" The quicksand under our feet is getting thicker and thicker. ”

Tang Yue squatted down, and the sand that originally only submerged his ankles had really reached his calves.

"What does this mean?"

"Means we're leaving the plains of Ishidi." The old cat replied, "The landscape has changed dramatically. ”

"Does that mean we're on the right track?"

"No, we're leaving the plains of Ihidi either way...... Okay, you can move on, I've figured out where I am. The old cat straightened up and called out a string of numbers, "130.8, 158.4." ”

“130.8？ 158.4？ What is this thing? ”

"Our position in the coordinate system, I use the parking position of the Martian stray dog as the origin to build the polar coordinate and Cartesian coordinate system, I just told you, my stride length is strictly 0.4 meters, so every step I take is 0.4 meters." The old cat explained, "From the time I set out until now, I have walked five hundred and twelve steps, and I have advanced a total of two hundred and four meters. ”

"So where are we going to be?"

"Its location is presumably at (2498.2, 2506.6)."

"Is it accurate?"

"It's just as accurate as possible." The old cat shrugged, "Inertial navigation always accumulates errors." ”

Every five minutes, the old cat has to stop to determine the direction, the equal width of the two feet can theoretically ensure that it can go in a straight line, but in reality the situation is more complicated than the theory, the uneven terrain and obstacles sometimes make the old cat have to make a detour.

Tang Yue also followed the practice of counting steps, he closed his eyes and followed the old cat closely, and counted silently in his heart every time he took a step, but every time he counted a certain number of steps, he would be interrupted, it may have touched a stone, or it may have encountered a ravine, at this time the old cat would turn his head to remind him, and then find a way to cross the obstacle, and when Tang Yue got all this and then wanted to count again, he couldn't remember how many steps he had taken.

In the dark and lightless world, he couldn't feel that he was advancing, and he couldn't count how many steps he had taken would make Tang Yue lose his sense of distance.

"Tired?"

"Okay." Tang Yue took a breath, "How far have we gone?" ”

"Six hundred meters."

"Only six hundred meters?" Tang Yue was a little surprised.

"Yes."

"I feel like I've walked six kilometers that far." Tang Yue said, "It's strange...... Why do you feel so tired when you haven't walked far? ”

"Psychological stress." The old cat said, "Normal people will be under considerable psychological pressure when they move in the case of complete loss of vision, after all, you are not blind and cannot adapt to this state in a short time." ”

The sand under his feet was getting thicker and thicker, and the old cat and Tang Yue were slipping when they went uphill, they were climbing a tall sand dune, and the more they went uphill, the steeper the slope became, and in the end this person and a cat had to use all fours, Tang Yue grabbed the old cat's two hind legs, crawling on the dune, and his limbs were deeply sunk into the sand.

It is extremely inconvenient to move in the quicksand, and he can't find the point of focus, Tang Yue struggles to paddle and pull or step in place, the sand flows away from under his body, just like a beginner swimming in the water, the old cat's situation is not much better than him, it is crawling and struggling hard in front of Tang Yue, and finally three steps forward, and suddenly slipping under his feet and returning to the original point, rolling into Tang Yue's arms.

Tang Yue hugged it and lay on the sand panting.

"How are you?" Tang Yue's mask and the old cat's helmet were leaning together, and he turned on the light inside the Mingguang armor mask to illuminate his face, "Did you fall and hurt yourself?" ”

"I didn't hurt anything, I just went down." The old cat said, "Just now my left arm didn't listen to the call, and I couldn't use my strength...... This arm is almost dead. ”

"What's going on now?" Tang Yue knew that the old cat's left arm was an old injury, and there had been problems more than once along the way, and the symptoms were getting worse and worse.

The old cat tried to move his limbs, muttered for a few seconds, and shook his head, "I'm afraid it's not optimistic, the joints of the limbs are very stiff, we have been in the storm for too long, and the old cold legs will be guilty as soon as the temperature is low." ”

"Shall we take a break, then?"

"No, the longer it drags on, the worse it gets, and I may need to heat it up to get the internal temperature up." "But we obviously don't have that condition." ”

It is impossible to heat up, what is most lacking now is energy and electricity, Tang Yue's Mingguang armor has a thermal insulation and heating function, but the cabin suit on the old cat does not have it, the old cat wears the cabin suit just to prevent wind and sand, and there is not even a battery.

The old cat was silent for a moment, "Listen to Tang Yue, if you have to ...... alone"

"Shut up." Tang Yue interrupted it, "I'll teach you how to heat up, will friction generate heat?" Mechanical energy is converted into internal energy, yes, it is to rub hands, we rub our hands outdoors in winter to keep warm, Lao Wang Lao Tang and a few of them Gay are still bare and rubbing each other to keep warm...... You start rubbing your hands now, rubbing! Rub hard! ”

The old cat was stunned.

"As for the hurry, I'll figure out a way, don't want me to leave you here......" Tang Yue squatted down and pulled up the old cat's forelimbs, grabbed it around his shoulders and neck, and carried it up with a low roar, and finally straightened up with force, shook and stopped, "Don't want me to leave you here!" Don't even think about it...... If you can't walk, I'll carry you! ”